MOTION SYSTEM
This invention relates to a three degree of freedom motion generator for moving a payload above the surface, the motion generator comprising a rotatable platform arranged for rotation on a circular guide above the surface, at least three linear guides extending ray-wise above the surface from a centre, each linear guide having a linear guide carriage moveable thereon, a peripheral guide carriage pivotally mounted on each linear guide carriage about the periphery of the rotatable platform, and a plurality of actuators, whereby at least one actuator may be operated to exert a force between a peripheral guide carriage on the circular guide and the rotatable platform. Other aspects include a motion system, and vehicle driving simulators including such a motion generator.
This application is a National Stage Application, filed under 35 U.S.C. § 371, of International Application No. PCT/EP2020/025273, filed Jun. 11, 2020, which international application claims priority to and the benefit of United Kingdom Application No. 1908351.8, filed Jun. 11, 2019; the contents of both of which as are hereby incorporated by reference in their entireties.
BACKGROUND Related FieldThis invention relates to the field of motion systems. In particular, though not exclusively, the invention relates to motion generators, and to motion systems including such motion generators such as vehicle driving simulators, and to methods of using motion generators and motion systems, as well as to methods of their production.
Description of Related ArtA motion generator is a device capable of applying movements, forces and accelerations to a payload in one or more directions of degrees of freedom. The payload can be, for example, a human undergoing a simulated experience in a motion simulator. Alternatively, the payload may also be a further motion generator which is said to be in series with the first. One example of a primary motion generator having a payload comprising a further motion generator is given in EP2810268A which discloses a three degree of freedom motion generator in series with a six degrees of freedom motion generator which can sustain large movements in the horizontal plane using the primary motion generator, whilst simultaneously achieving the maximum vertical travel of the secondary motion generator. Motion generators are used in motion systems. Motion systems comprise at least one motion generator and at least one control system for controlling the motion generator. Motion generators and motion systems are used in a variety of applications, including motion simulation (for example, flight simulators, driving simulators), robotics, 3D printing, vibration and seismic simulation. The most common type of motion generator currently used in motion simulation is the Stewart platform (or“hexapod”). This is a type of parallel robot that has six actuators, attached in pairs to three configurations on the baseplate of a platform and crossing over to three mounting points on a top plate. Devices or payloads such as a human user placed on the top plate, usually in some form of cockpit, chassis driver area, or model vehicle, can be moved in the six degrees of freedom in which it is possible for a freely-suspended body to move, i.e. the three linear movements x, y, z (lateral, longitudinal and vertical), and the three rotations (pitch, roll and yaw). A motion simulator is a mechanism that can create, for an occupant, the effects or feelings of being in a moving vehicle. Motion simulators are used, professionally, for training drivers and pilots in the form of driving simulators and flight simulators respectively. They also are used, industrially, in the creation, design, and testing of the vehicles themselves. Professional motion simulators used for driving and flying simulators typically synchronise a visual display—provided for example by a projection system and associated display screens and audio signals with the movement of a carriage (or chassis) occupied by the driver or pilot in order to provide a better sensation of the effect of moving. The advent of virtual reality (VR) head-mounted displays (HMDs) makes the aspect of an immersive simulation less costly with current motion systems and has the ability to deliver virtual reality applications to leisure uses such as in passive amusement park or arcade driving, riding-first-person, or flying rides and in active gaming, where one or more players has some control over the driving, riding, flying or first-person game experience. The type of hexapod-based motion systems typically used for motion simulation for human participants typically have a relatively low bandwidth of up to about 20 Hz. This means that they can create oscillatory movements and vibrations of a consistent amplitude, with a frequency of up to 20 times per second, beyond which the amplitude of the movements reduces as the frequency increases. This is sufficient for replicating most car suspension movements, but it does not transmit the frequency content associated with vibrations from the car engine, tyre vibrations, road noise, and the sharp-edged kerbs on racetracks. A low bandwidth also means the signals are delayed, meaning that the driver cannot respond as quickly. One example of a hexapod-based driving simulator is known from WO2014/1 14409.
Current motion simulation systems, especially those intended for high-end use such as in military and commercial flight instruction and training applications, are typically very large, heavy, complex, and very expensive. Their complexity necessitates extensive programming and maintenance, further extending the cost to users. Dedicated vehicle driving simulator motion systems have been developed by the likes of McLaren/MTS Williams/AIM and Ansible, but these tend to be extremely mechanically complex, and therefore expensive, featuring precision machined custom components and often expensive linear motors. These dedicated vehicle driving simulator motion systems are more responsive than hexapods when moving in some directions but are still limited in others. The use of ball screws in such systems is disadvantageous in that, whilst good at establishing position, they inhibit force transfer and can only achieve a lower bandwidth. This results in a less natural experience for a human user.
A further disadvantage of hexapod-based motion generators is that they lack an ability to rotate about a vertical axis beyond about 25° in either direction of rotation from a nominal position. One attempt at providing more rotation about a vertical axis is disclosed in EP3344352A, in which a motion generator having a carriage with cables operated by respective cable drives wound round the carriage in alternate directions whereby the carriage can rotate through at least 90° by operation of the cable drives. One attempt at introducing rotation into a hexapod-based system is disclosed in US2005/0042578 in which a vehicle chassis is mounted on a rotary plate above a Stewart platform. However, the apparatus is not compact in the vertical direction, which may necessitate a bigger room for installation, and the length and nature of the actuators inhibit precise control. In the apparatus disclosed in US2015/004567, which is intended to be more compact than previous designs of motion generators, rotation of a mobile platform is limited to relatively small degrees of yaw.
An object of the present invention is to provide an improved motion generator, and improved motion systems incorporating such motion generators, having improved yaw characteristics.
BRIEF SUMMARYAccording to one aspect of the invention there is provided a motion generator for moving a payload above the surface in three degrees of freedom, the motion generator comprising a rotatable platform arranged for rotation on a circular guide above the surface, at least three linear guides extending ray-wise above the surface from a centre, each linear guide having a linear guide carriage movable thereon, a peripheral guide carriage mounted for rotation on each linear guide carriage adjacent the periphery of the rotatable platform, and a plurality of actuators, in which at least one actuator may be operated to exert a force between a peripheral guide carriage and the rotatable platform whereby the platform may be rotated, and/or translated above the surface.
Such a 3DOF (i.e. movements in the X and Y directions, and yaw) motion generator may be advantageous, especially in vehicle driving and flying simulation applications, in that it may be able to rotate the platform through 360° or more. The motion generator may be further advantageous in that it may have good levels of excursion i.e. the platform may be caused to move one or more metres in a horizontal direction (i.e. translate) with respect to the surface. Such a combination of high levels of platform rotation and excursion are highly advantageous in a motion generator for vehicle driving simulation applications. Furthermore, the motion generator of the invention may be advantageously compact in height.
The linear guides may typically be mounted on the surface, and the circular guide may be on the rotatable platform. The linear guide carriages may be driven to move on the linear guides by, actuators, in order to translate the linear guide carriages along the linear guides. At least one of these actuators may comprise a linear motor, as they permit high levels of movement control, although the skilled addressee will appreciate that other actuators may be used. Preferably, each of the actuators comprises a linear motor.
The peripheral guide carriages may be arranged at least partly below the platform. At least a portion of the peripheral guide carriages may extend about an outer edge of the platform. The peripheral guide carriages are mounted for rotation on the peripheral guide carriages and may be, for example, pivotally mounted thereon. In one embodiment, one of the peripheral guide carriages and the rotatable platform includes at least one linear motor coil which interacts with a
corresponding linear motor magnet way on the other of the peripheral guide carriages and the rotatable platform to rotate the platform. In a preferred embodiment, the peripheral guide carriage comprises the linear motor coil and the rotatable platform comprises or supports the corresponding linear motor magnet way. In order to enhance operation, the or each linear motor magnet way may be curved. The or each linear motor coil may be correspondingly curved.
In another embodiment, at least one actuator for rotating and/or for translating the platform comprises a belt drive. For example, a suitable belt drive may be an omega belt drive. The belt, which may be toothed or flat, may extend about or at the periphery of the platform.
In another embodiment, at least one actuator for rotating the platform comprises a gear ilich drives a correspondingly toothed rim on or fast with the platform to rotate the platform. The rim may be arranged at or about the periphery of the platform.
In operation, movement of two adjacent linear guide carriages along their respective linear guides towards the centre may move the rotatable platform above the surface along or in the direction of another linear guide, that is to say generally along the longitudinal axis of the linear guide, away from the centre. Conversely, movement of two adjacent linear guide carriages along their respective linear guides away from the centre moves the rotatable platform above the surface along or in the direction of another linear guide towards the centre.
As noted above, the rotatable platform may rotate up to 360° or by more than 360° providing very, useful levels of yaw, for example for vehicle driving simulation. In this connection, the payload of the motion generator may be a vehicle chassis or cockpit or model thereof. In the context of the present invention, the payload of the primary motion generator is typically greater than 80 kg. The primary payload may include a human user, or vehicle or model of all or part of a vehicle. Thus, the payload may typically be more than about 80 kg, or more than about 250 kg, or more than about 500 kg, or more than about 2 tonnes (for example in the form of a full vehicle chassis).
According to another aspect of the invention there is provided a motion system comprising a motion generator according to the invention, and a control system arranged to control operation of the motion generator.
According to another aspect of the invention there is provided a combination comprising a first (or primary) motion generator or motion system according to the invention together with a second (or secondary) motion generator including a second motion generator platform for supporting a payload, the secondary motion generator being mounted on the rotatable platform of the first motion generator or motion system. The secondary motion generator may be a 3, 4, 5, or 6° of freedom motion generator. Such a combination is advantageous in that the primary motion generator gives significant levels of excursion with high precision and the secondary motion generator provides motion for the payload of the secondary in additional or all degrees of freedom.
According to another aspect of the invention there is provided a vehicle driving simulator including a motion generator according to the invention or a motion system according to the invention, or a combination of motion generators according to the invention, a vehicle body element such as a chassis, or indeed full body, and including at least one environment simulation means selected from visual projection or display means, and audio means. Preferably, the projector and/or display means extends completely around the rotatable platform. In one embodiment, the projection and/or display means is mounted on or about the rotatable platform. Where the projection and/or display means is mounted on the rotatable platform it may move with the platform.
According to a further aspect of the invention, there is provided a method of producing a motion generator according to the invention, the method comprising providing a rotatable platform which can be arranged for rotation on a circular guide above an operational surface, arranging at least three linear guides to extend ray-wise above the surface from centre, providing each linear guide with a linear guide carriage movable thereon, mounting a peripheral guide carriage for pivota.ble movement on each linear guide carriage at or about the periphery of the platform, and providing a plurality of actuators, whereby, in use, each actuator may be operated to exert a force between a peripheral guide carriage on the circular guide and the rotatable platform.
Motion generators, motion systems and vehicle driving simulators in accordance with the invention will now be described, by way of example only, with reference to the accompanying drawings,
Motion Generator
In use under the control of a control system (for example as described above in relation to
The movement of the linear guide carriages and peripheral guide carriages of the motion generator in accordance with the invention are described in more detail below.
Motion Generator
A motion generator 400 in accordance with another embodiment of the invention is shown in
Motion Generator
In a further embodiment of a motion generator in accordance with the invention, the omega belt drive actuators described in relation to the motion generator described in
Combination of Motion Generators
A combination comprising a primary motion generator 600 (which is a motion generator in accordance with the invention) in series with a further motion generator, to form a combination is shown in
In use, the platform 602 is rotated with great precision about a vertical axis through operation of some or all of the linear motors 604LM, 606LM, 608LM, and 61 OLM respectively under the control of a control system (for example as described in relation to
The motion generator 600 described above demonstrates good levels of excursion which is useful, for example, in vehicle driving simulation. For example, platform 602 may move 2 metres in any, horizontal direction from the centre. Furthermore, the secondary motion platform provides additional motion. It will be noted that only a limited number of conditions is described above. It will be appreciated by the skilled addressee that the primary 600 and secondary motion generators 630 may be operated independently or in combination to move chassis 616 into many more conditions such as those described above and below and including, but not exclusively surge rearward, sway right, heave down, roll left side down, pitch nose up and yaw nose right. For example,
Control System
Method of Operating a Motion Generator/Motion System
The motion generators described above can be combined with a control system (for example, as described in relation to
Nominal
In
Surge Rearward
In
Surge Forward
In
Sway Rightward
In
Sway Leftward
In
Yaw Anticlockwise
In
Yaw Clockwise
In
Extreme Yaw
In
Vehicle Driving Simulator
A vehicle driving simulator 50 in accordance with the invention is shown in
Method of Producing a Motion Generator
Motion generators, motion systems, and vehicle driving simulators in accordance with the invention can be produced by conventional methods of construction and manufacture. Frequently off-the-shelf components may be used in their production.
Whilst the invention has been described in particular in relation to the use of motion generators in vehicle motion simulation applications, the skilled addressee will appreciate that the motion generators and motion systems of the invention will find other applications such as flying vehicle simulation and in particular simulating rotorcraft. The skilled addressee will also appreciate that numerous modifications and alterations can be made to the above embodiments, which are given by way of example only, without departing from the scope or spirit of the invention.
Claims
1. A motion generator for moving a payload in three degrees of freedom above the surface, the motion generator comprising a rotatable platform arranged for rotation on a circular guide above the surface, at least three linear guides extending ray-wise above the surface from a centre, each linear guide having a linear guide carriage moveable thereon, a peripheral guide carriage mounted for rotation on each linear guide carriage about the periphery of the rotatable platform, and a plurality of actuators, whereby at least one actuator may be operated to exert a force between a peripheral guide carriage and the rotatable platform to rotate the platform and in which the rotatable platform may also be translated above the surface by the operation of at least one actuator.
2. The motion generator according to claim 1, in which the rotatable platform may be simultaneously rotated and translated.
3. The motion generator according to claim 1, in which the linear guides are mounted on the surface.
4. The motion generator according to claim 1, in which the circular guide is on the rotatable platform.
5. The motion generator according to claim 1, in which the linear guide carriages can be driven to move on the linear guides by actuators.
6. The motion generator according to claim 1, in which either: at least one of the actuators comprises a linear motor; or all the actuators comprise a linear motor.
7. (canceled)
8. The motion generator according to claim 1, in which one of the peripheral guide carriages and the rotatable platform includes at least one linear motor coil which interacts with a corresponding linear motor magnet way on the other of the peripheral guide carriages and the rotatable platform to rotate the platform.
9. The motion generator according to claim 1, in which:
- the peripheral guide carriage comprises the linear motor coil(s) and the rotatable platform comprises the corresponding linear motor magnet way, and
- one or more of: the, or each, linear motor magnet way is curved, or the, or each, linear motor coil is curved.
10. (canceled)
11. (canceled)
12. The motion generator according to claim 1, in which:
- at least one actuator comprises a belt drive, and
- one or more of: the said at least one actuator is operable to rotate the rotatable platform, or the belt-drive is an omega belt drive.
13. (canceled)
14. (canceled)
15. The motion generator according to claim 1, in which at least one actuator comprises a gear which can drive a corresponding toothed rim on the platform to rotate the platform.
16. The motion generator according to claim 1, in which movement of two adjacent linear guide carriages along their respective linear guides towards the centre moves the rotatable platform above the surface away from the centre.
17. The motion generator according to claim 1, in which movement of two adjacent linear guide carriages along their respective linear guides away from the centre moves the rotatable platform above the surface towards the centre.
18. The motion generator according to claim 1, in which the rotatable platform can rotate by up to, or more than, 360 degrees.
19. The motion generator according to claim 1, in which the payload is a vehicle chassis or cockpit or model thereof.
20. A motion system comprising:
- a motion generator according to claim 1, and
- a control system arranged to control operation of the motion generator.
21. A combination comprising:
- a first motion generator according to claim 1 as a primary motion generator/motion system, and
- a secondary motion generator on the rotatable platform of the first motion generator.
22. A combination according to claim 21, in in which the secondary motion generator is a 3, 4, 5 or 6 degrees of freedom motion generator.
23. A vehicle driving simulator comprising:
- a motion generator according to claim 1, and
- at least one environment simulation means selected from visual projection or display means, and audio means.
24. A vehicle driving simulator according to claim 23, in which the projection or display means extends completely around the rotatable platform.
25. A vehicle driving simulator according to claim 23, in which the projection and or display means is mounted about the rotatable platform, preferably for movement linked to the platform.
26. A method of producing a motion generator according to claim 1, the method comprising:
- providing a rotatable platform arranged for rotation on a circular guide above the surface,
- arranging at least three linear guides to extend ray-wise above the surface from a common point,
- providing each linear guide with a linear guide carriage moveable thereon, a peripheral guide carriage pivotally mounted on each linear guide carriage about the periphery of the platform, and a plurality of actuators,
- whereby, in use, each actuator may be operated to exert a force between a peripheral guide carriage on the circular guide and the rotatable platform.
Type: Application
Filed: Jun 11, 2020
Publication Date: Aug 11, 2022
Inventors: Ashley William Hawker WARNE (Bristol), Matthew Peter BELL (Bristol), Daniel Charmbury WARD (Bristol), John Paul DEAN (Bristol)
Application Number: 17/617,201